Multi-RAT in which heterogeneous communication networks are merged has been researched. For example, a multi-RAT user equipment (UE) supports both a cellular network and a wireless local area network (WLAN). Such a multi-RAT UE can selectively access any one of a plurality of RATs but cannot simultaneously access the plurality of RATs. That is, even when a UE has multi-RAT capabilities, the UE cannot simultaneously transmit and receive data via different RATs.
If a UE transmits data, transmit power used by the UE is restricted to a predetermined range. The transmit power of the UE may be restricted for various reasons. For example, maximum transmit power of a UE may be restricted in order to reduce interference with another UE, to more efficiently use power of the UE or to reduce influence of a radio frequency (RF) signal transmitted by the UE on a human body.
In the related art, when a multi-RAT UE accesses one of the first and the second RATs, transmit power of the UE is restricted according to the policy of the RAT. However, the related art does not consider transmit power of a UE and data transmission and reception scheduling of the UE when a multi-RAT UE simultaneously accesses a plurality of RATs.